It will be remembered that, in the arrangement here followed, Dr. Gadow placed the _STEREORNITHES_ under the head of Neornithes Ratitae, though not under that of Ratitae in the restricted {44}sense; but it should be noted that their systematic position was not by any means assured, though justified by what was then known of these extraordinary fossils, of which the sternum has not even yet been brought to light. Remains of various forms, chiefly of gigantic size, have been disinterred from the Miocene strata of Santa Cruz in Patagonia, one of which (_Phororhachos_) was described in 1887 by Dr. Ameghino,[37] from its mandible as an Edentate Mammal, though four years later[38] he arrived at the more correct conclusion that the jaw was to be referred to a bird. In 1891, moreover, Señores Moreno and Mercerat[39] proposed a new Order with the name of _Stereornithes_, when publishing a series of fine plates; while Dr. Ameghino, who criticised their work, reduced the nine genera created therein to the smaller number of three.[40] Another paper by the author last named,[41] and two by Mr. Lydekker[42] should be consulted by those interested in the details of the subject, while an admirable summary will be found in Professor Newton's _Dictionary of Birds_. In a review of Dr. Ameghino's paper on these birds,[43] Mr. C. W. Andrews stated that _Phororhachos_ and others of the "Stereornithes" were not truly Ratite, but were Carinate forms in which the wings had undergone reduction, and suggested that possibly they were related to the parent stock of the Gruiformes, approximating particularly to _Cariama_ (_Dicholophus_). Shortly afterwards Dr. Ameghino's collection was acquired by the British Museum, and a study of the specimens themselves has not caused the reviewer to change his opinion.[44] Some members of the group (e.g. _Mesembriornis_) are perhaps truly Ratite, and one at least (_Dryornis_) belongs to the _Cathartidae_. _Phororhachos_ is remarkable for the immense size and heavy build of the skull, to which the legs, huge though they sometimes are, bear no proportion; the maxilla is exceedingly compressed, yet very deep, and ends in a strong hook, while the long massive mandible curves upwards to meet it. There is a quite or nearly complete interorbital septum in this case, as opposed to _Apteryx_, and, to a considerable extent, to the Dinornithidae; {45}while the nostrils are pervious, and the quadrate articulates with the skull by two heads, contrary to what occurs in the Ratitae proper. The furcula is existent, but extremely slender; the metatarsus is more or less elongated, the hallux is present, the wings are small but well developed, and the tail is said to be long, with a considerable number of separate vertebrae.